A leak from a hydraulic circuit, in particular a circuit belonging to the engine of a motor vehicle, can have consequences that are disastrous, running the risk of destroying the engine, or even worse, putting the safety of the occupants of the vehicle in danger. Consequently, the automobile industry uses tubular duct connectors of lifetime greater than that of the vehicle fitted therewith. Such connectors generally give satisfaction, but they are complex in structure and consequently high in price since they include a large number of parts.